JP2533685B2 - Low-pressure CVD gas introduction device and method for forming the device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a film-forming source gas introduction apparatus used in a low-pressure CVD apparatus for vapor-depositing a thin film on the surface of a semiconductor substrate in a reduced-pressure film-forming source gas atmosphere. Then, from a plurality of pipes for transporting different kinds of gases, the raw material gas introduced into the vacuum container through the wall of the vacuum container whose inside is kept in a depressurized state or the fixing member on the vacuum container side is introduced. The composition of a gas introduction device for mixing and supplying the mixed raw material gas to the surface of a film formation substrate in a vacuum container to vapor-deposit a thin film on the surface of the substrate, and a gas introduction device of this structure are formed. With respect to the method.

[Conventional technology]

FIG. 3 shows a configuration example of a conventional gas introducing device of this type. In this example, the target low pressure CVD equipment is plasma CVD
The source gas A, B is introduced into the flat circular buffer pocket on the front side of the base electrode 4 through the pipes 1 and 2 penetrating the supporting portion of the base electrode 4 for forming plasma in the vacuum container 3, respectively. Are mixed.
Then, with the pressure kept constant, a large number of pores are supplied to the surface of a film formation substrate (hereinafter also referred to as a wafer) 9 from shower electrodes 5 formed at equal pitches. Therefore, in this example, the gas introduction device is composed of the base electrode 4, the shower electrode 5, and the screw 8 connecting the both.

When forming a thin film on the surface of the wafer 9, after heating the wafer by supplying power to the heater 11 built in or embedded in the substrate table 10 on which the wafer is placed, the raw material gas A, While supplying B to the surface of the wafer 9 from the shower electrode 5, a high frequency voltage is applied from the RF power source 13 to the base electrode 4 to form plasma in the space between the shower electrode 5 and the wafer 9. Reference numeral 7 in the drawing is an insulating bush for insulating the supporting portion of the base electrode 4 from the vacuum flange 3b, and reference numeral 12 is a substrate stand 10 via a screw rod 13.
Is a motor for vertically moving to adjust the distance between the shower electrode 5 and the wafer 9 to a desired value.

FIG. 4 shows another example of the configuration of the conventional gas introduction device. In this example, the buffer plate 16 is provided in the space formed by the base electrode 4 and the shower electrode 5, and the mixing process of the raw material gas until it is jetted from the shower electrode 5 is lengthened to make the mixing more uniform and By flowing the gas in the radial direction, the pressure in the buffer pocket is made uniform and the surface distribution of the injection flow rate is made uniform.

[Problems to be Solved by the Invention]

In the case of the gas introduction device shown in FIG. 3, the shower electrode has a large number of pores dispersed uniformly.
The raw material gas passing through 2 directly hits the shower electrode, and although there is a buffer pocket for the purpose of injecting the raw material gas from the shower electrode toward the wafer surface at a constant pressure, the pressure is high near the electrode part where the direct gas flow hits, and A large amount of raw material gas is ejected. As a result, in the case of ordinary thin film formation, the film thickness distribution on the wafer surface becomes non-uniform. Further, in order to solve this problem, a buffer plate is provided as shown in FIG. 4, and the raw material gas ejected from the pipe is once applied to the buffer plate to diffuse it in the radial direction to make the pressure uniform. However, the surface distribution of pressure is not sufficiently uniform and the mixed state of the raw material gas is improved as compared with FIG. 3, but the film thickness distribution is insufficient and ± 5% is the guaranteed range. it is conceivable that.

Another problem of the gas introduction device shown in FIGS. 3 and 4 is the film adhesion to the shower electrode during film formation. That is, when the film is formed, the film is attached to the shutter electrode, the pores of the raw material gas jet are blocked, and the film thickness distribution becomes large, or the film attached to the shower electrode is peeled off to become particles to contaminate the film formation substrate. For this reason, the shower electrode needs to be regularly cleaned. Conventionally, the shower electrode is fixed at its outer periphery with four or more screws, as shown in Fig. 3, and it takes time just to remove it, and the screws are usually flat head screws or hexagon socket bolts. The heads of these screws have a hook groove for a driver or a wrench, but this groove is filled with a film, so that the driver or the like cannot be sufficiently hooked and it may be difficult to remove. In this case as well, it took time and there was a problem in using the screw.

An object of the present invention is to provide a gas introduction device in which raw material gases ejected from a plurality of pipes are more uniformly mixed and the ejection amount surface distribution of a mixed gas ejected toward a surface of a substrate to be processed is made more uniform. And a method of forming a device of this configuration.

[Means for solving the problem]

In order to solve the above-mentioned problems, in the present invention, a plurality of pipes respectively transporting different kinds of gas are passed through a wall of the vacuum container whose inside is kept in a depressurized state or a fixing member on the vacuum container side. A gas introduction device for mixing the raw material gases introduced into the vacuum container, supplying the mixed raw material gas to the surface of the film formation substrate in the vacuum container, and performing vapor phase growth of a thin film on the substrate surface, The gas, which is formed in a disc shape and flows out from each of the pipes, is received on each surface and is evenly distributed to a plurality of holes formed at equal intervals in the circumferential direction,
The same number of separator plates as the pipes, a mixing spacer for forming a first space for mixing the gas flowing out from the plurality of holes of the respective separator plates, and rectifying the mixed gas in the first space A first rectifying plate having a large number of pores formed therein, and a second mixing spacer for forming a second space that makes the mixed state of the gas flowing out from the first rectifying plate more uniform, The second rectifying plate having a large number of pores for rectifying the mixed gas in the second space, and the separator formed as a ring-shaped body having a hole having a diameter smaller than the outer diameter of the second rectifying plate. Among all the members from the plate to the second rectifying plate, at least the members excluding the separator plate are held in a laminated state on the wall surface of the vacuum container or the holding member on the vacuum container side, and a pressing plate is provided. And the. The formation of this device is performed by forming all the members from the separator plate to the second rectifying plate coaxially in the above order, and receiving the gas on the surfaces of the separator plates formed at equal intervals in the circumferential direction on each separator plate. Are evenly distributed so that multiple holes do not overlap in the axial direction and all separator plates are in close contact with each other and stacked,
It is performed by using a holding plate formed as a ring-shaped body and holding it on the wall surface of the vacuum container facing the film formation substrate or on a fixing member on the vacuum container side. Then, this device is detachably formed on the wall surface of the vacuum container or the fixing member on the vacuum container side, and all the members from the separator plate to the second rectifying plate are coaxially and at least the first mixing plate in the mounted state. A ring-shaped base mount having a camera mount that accommodates all the members from the spacer to the second rectifying plate so as to be able to be taken in and out in the axial direction, and the base mount as a holding plate formed as a ring-shaped body. It is preferable to use an apparatus that includes a press mount that fits into the base mount and that is attached to and detached from the base mount by rotation.

[Action]

By forming the gas introduction device as described above, a plurality of holes formed at equal intervals in the circumferential direction in each separator plate,
The different source gases, which are present in the circumferential direction evenly dispersed in the axial direction and are received on the surfaces of the respective separator plates, are circumferentially uniformly dispersed and ejected into the first space, To uniformly mix toward the center of the space, and increase the pressure in this space to a constant value. Then, the raw material gas mixed in the first space is divided into the number of pores from the pores of the same diameter formed by being evenly dispersed in the first rectifying plate, and the second raw material gas is laminarly flowed. Of the gas is mixed therein while filling the space between the gas regions ejected from the respective pores, and the pressure in the space is increased to a constant value while further increasing the uniformity of mixing. The mixed gas is further diverted from the second rectifying plate, in which a large number of pores having the same diameter are uniformly dispersed and formed, and jetted toward the surface of the film formation substrate, and the front surface side space of the substrate is formed. In the chamber, the flow rate is guided to the surface of the substrate at a constant flow rate and with a uniform surface distribution of the flow rate while increasing the uniformity of mixing.

Further, the gas introducing device is detachably formed on the wall surface of the vacuum container or on the fixing member on the vacuum container side, and all the members from the separator plate to the second rectifying plate are coaxial with each other in the mounted state, and at least the first member. A ring-shaped base mount having a camera mount for accommodating all the members from the mixing spacer to the second rectifying plate so as to be able to be taken in and out in the axial direction, and the base mount as a holding plate formed as a ring-shaped body. An apparatus having a holding ring that is attached to and detached from the base mount by rotation with a camera mount that fits with the separator plate, and the separator plate is in close contact with the wall surface of the vacuum container or the fixing member on the vacuum container side when forming the device. After mounting the base mount, attach the base mount to the wall of the vacuum container or the fixing member on the vacuum container side, A gas introduction device is formed by accommodating the remaining components coaxially, fitting the camera mount of the base mount and the camera mount of the press ring, and rotating the press ring to attach it to the base mount. The components can be easily taken out by simply rotating the pressing ring and removing them, compared with the conventional device that requires many screws to be removed.
Maintenance time can be greatly reduced. Also, the screw that attaches the base mount to the wall of the vacuum container or the fixing member on the vacuum container side is hidden by the pressing ring, and the film does not adhere to the screw. It will be easier.

〔Example〕

FIG. 1 shows an exploded perspective view of an embodiment of the gas introducing device structure according to the present invention, and FIG. 2 shows the overall structure of the film forming section of a low pressure CVD device including this device. First, referring to FIG. 2, the overall structure of the film forming processing section will be described.

The vacuum container 43 includes a container main body 43a, an upper flange 43b, and a lower flange 43c as main members, and the lower flange 43c is connected to the substrate table 10 via a metal bellows 15 so as to be vertically movable. (Reference numeral in FIG. 3
It is driven linearly in the vertical direction according to (12). A concave surface is formed on the upper surface of the substrate table 10 in accordance with the outer diameter of the wafer 9 so that the wafer 9 can be placed at a fixed position. Waha 9
With a wafer transfer device (not shown), a gate valve between the container body 3a and a load lock chamber (not shown) can be opened to freely move in and out in the left and right directions in the drawing. A base 44 is attached to the upper flange 43b via an insulating ring 14. The same number of pipes as the types of raw material gas, here two pipes 1 and 2 for attaching the raw material gas, are attached to the upper surface of this stand 44 via an insulator. The raw material gases 17 and 18 are supplied from gas cylinders and the like provided separately. The pipes 1 and 2 and the base 44 are vacuum-sealed with an O-ring, and the base 44 is formed with through holes through which the raw material gases 17 and 18 pass. Here, the raw material gas 17 passing through the pipe 1 will be referred to as a gas A, and the raw material gas 18 passing through the pipe 2 will be referred to as a gas B for convenience of description of gas introduction described later.

A terminal conductor 45 connected to an RF power source for causing plasma discharge is attached to the table 44. On the vacuum side of the table 44, a separator plate, a first mixing spacer, which will be described later,
The gas introducing device 100 including the first rectifying plate, the second mixing spacer, and the second rectifying plate forming the shower electrode 31 is attached. A vacuum seal is provided between the table 44 and the vacuum container 43 with an O-ring, and the inside of the vacuum container 43 is evacuated by a separately provided vacuum pump.

Here, the film forming procedure in the film forming processing section will be briefly described.

The inside of the vacuum container 43 is evacuated in advance, and the wafer is placed on the upper surface of the substrate table 10 by a separately provided wafer transfer device. The substrate table 10 is kept at a preset temperature such as 400 ° C. in advance, and the temperature of the wafer 9 is raised. When the wafer is placed on the upper surface of the substrate table 10, the substrate 10 is lifted by the up-and-down driving device and stops while maintaining a set gap with the shower electrode 31. When the temperature of the wafer 9 becomes constant, a high frequency voltage, for example, 13.56 MHz voltage is applied to the base 44 from the RF power source through the terminal conductor 45. Subsequently, when the predetermined raw material gases A and B are introduced from the pipes 1 and 2 and passed through the gas introduction device, the constant pressure mixed and rectified raw material gas is ejected from the shower electrode 31, whereby plasma of the raw material gas is generated. The generated raw material gas is activated and deposited on the surface of the wafer 9. The raw material gas is flown for a predetermined time to complete the film formation.

 Next, the gas introduction device will be described.

In FIG. 1, two sets of a separator plate 20 and a separator plate 21 for radially distributing the gas A and the gas B respectively received on the surface are held by a mounting screw 22 on a base 44 which is a reference for assembly. It Separator plate 20
A groove 23 having an appropriate width is formed radially in the radial direction from the center, and a through hole 24 is formed at the end thereof to form a path through which the gas A flows. At the same time, the separator plate 21 also has a circular groove, and the circular groove radially extends from the circular groove.
The same number of grooves as the grooves of the separator plate 20 are formed, and the through holes 26 are formed at the tips of these grooves, respectively. Also,
At the center of the separator plate 21, a small hole for guiding the gas A onto the surface of the separator plate 20 is formed. The separator plate 20 is formed with a hole 27 for passing the gas B flowing out from the separator plate 21 downward.

Next, the first mixed spacer 28 will be described. The spacer is provided to form a space in which the gas A passing through the separator plate 20 and the gas B passing through the separator plate 21 are uniformly mixed. Gas A
And gas B are the separator plate 20 and the separator plate, respectively.
After separating into a plurality of holes in the circumferential direction with 21, the separator plate
21, the first mixing spacer 28, and a first rectifying plate 29, which will be described below, flow into a space and are mixed there to raise the pressure in the space to a constant pressure.

On the first rectifying plate 29, for example, pores having a diameter of 0.5 mm are uniformly and accurately arranged. First straightening plate 29
Is to divide the raw material gas mixed in the space into a flow passing through the pores to make a laminar flow. First straightening plate
A space having a height of 1 mm to 3 mm is formed between the 29 and the second rectifying plate 31 by using the second mixing spacer 30, and the raw material gas that has flowed in as a laminar flow is uniform here as well. The second pressure is constant while being mixed into
It is jetted as a laminar flow from, for example, a 0.5 mm diameter fine hole formed in the straightening plate 31.

The first mixed spacer 28 and the second mixed spacer 30 are formed to have the same radial dimension, and the inner diameter thereof is the separator plate.
It is slightly larger than the outer diameter of 20,21. Therefore, the second rectifying plate 31 and the second mixing spacer 30
Then, the first rectifying plate 29 and the first mixing spacer 28 are coaxially overlapped and come into contact with the base 44. Also,
In the base mount 32, the raw material gas is the member 31, 30, 29, 2 described above.
In order not to flow out from the outer peripheral surface side of 8, the inner peripheral surface for accommodating these members is formed in a size that is in close contact with these members over the entire outer peripheral surfaces of these members, and is mounted by a mounting screw 33. It is attached to 44.

The base mount 32 is provided with three nail-shaped camera mounts 35 that are often used in lens cameras.
Second straightening plate in combination with base mount 32
The holding ring 34 that supports the peripheral portion of the base 31 and prevents the members from the second rectifying plate 31 to the first mixing spacer 28 is removed, and has a groove shape that fits the claw-shaped camera mount of the base mount 32. A camera mount 36 is formed, and a ring groove for accommodating the claw-shaped camera mount 35 is formed at the axial end portion thereof. Therefore, after the groove-shaped camera mount 36 of the pressing ring 34 is fitted with the claw-shaped camera mount 35 of the base mount 32, by rotating the pressing ring 34, the pressing ring 34 is held by the base mount 32 and constitutes a shower electrode. The upper member including the second rectifying plate 31 is prevented from falling.

In the above description, the low-pressure CVD apparatus to which the gas introduction apparatus of the present invention is attached is a plasma CVD apparatus, but the gas introduction apparatus of the present invention can of course be applied to a thermal CVD apparatus, and the source gas is mixed in advance. It is needless to say that it can be applied as a gas introduction device for uniformizing the surface distribution of the amount of supply to the wafer surface when it is supplied from a single pipe in this state.

〔The invention's effect〕

As described above, in the present invention, since the gas introduction device is formed of the above-mentioned members and is formed according to the above-described forming method, the surface distribution of the ejection amount of the raw material gas ejected from this device And the state of mixing of the source gases is made much more uniform than before, and the film thickness distribution of the thin film formed on the wafer surface is kept within 3% without impairing the film formation rate. Became possible. In addition, since the second rectifying plate whose surface is contaminated during film formation is replaced by attaching and detaching the camera mount type retaining ring, the conventional mounting screws are not required and maintenance time is shortened. Then, we were able to eliminate the troubles associated with disassembly.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing the structure of a gas introducing apparatus according to an embodiment of the present invention, and FIG. 2 is an overall structure of a film forming processing section of a low pressure CVD apparatus equipped with the gas introducing apparatus shown in FIG. FIG. 3 is a side cross-sectional view showing an example, and FIGS. 3 and 4 are whole and partial cross-sectional views of a film forming processing section showing different configuration examples of a conventional gas introducing device, respectively. 1,2: Piping, 3,43: Vacuum container, 6,100: Gas introduction device, 9: Substrate to be film-formed (wafer), 17: Gas A (raw material gas), 18: Gas B (raw material gas), 20: Separator Plate (for gas A), 21:
Separator (for gas B), 28: First mixed spacer, 29:
First straightening plate, 30: second mixed spacer, 31: second
Rectifying plate (shower electrode), 32: base mount, 34: retaining ring, 35, 36: camera mount.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yasuhiro Noji 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd.

Claims (3)

(57) [Claims] 1. A raw material introduced into a vacuum container from a plurality of pipes for respectively transporting different kinds of gas, penetrating a wall surface of the vacuum container whose inside is kept in a depressurized state or a fixing member on the vacuum container side. In a gas introduction device for mixing gases, supplying the mixed raw material gas to the surface of a substrate to be film-formed in a vacuum container, and performing vapor phase growth of a thin film on the surface of the substrate, each of the above-mentioned disc-shaped devices is formed. The gas flowing out from the pipes is received on each surface and is evenly distributed to a plurality of holes formed at equal intervals in the circumferential direction. The same number of separator plates as the pipes and the plurality of holes of the respective separator plates flow out. Mixing spacer for forming a first space for mixing the mixed gas, a first rectifying plate having a large number of pores for rectifying the mixed gas in the first space, and the first rectifying plate. Flow from plate A second mixing spacer for forming a second space for making the mixed state of the mixed gas more uniform, and a second rectification in which a large number of pores for rectifying the mixed gas in the second space are formed. The plate and a member formed as a ring-shaped body having a hole having a diameter smaller than the outer diameter of the second rectifying plate and having at least the separator plate among all the members from the separator plate to the second rectifying plate are laminated. A pressure reducing device comprising: a holding plate that holds the wall of the vacuum container or a fixing member on the vacuum container side.
CVD gas introduction device. 2. A method for forming the gas introducing device according to claim 1, wherein all the members from the separator plate to the second rectifying plate are coaxial with each other in the order of claim 1. , And that each separator plate is formed at equal intervals in the circumferential direction so that the gas received on the surface of the separator plate is evenly distributed. Then, by using a holding plate formed as a ring-shaped body is held by the wall surface of the vacuum container facing the film formation substrate or a fixing member on the side of the vacuum container to form the reduced pressure CVD gas introduction device. Forming method. 3. The gas introducing device according to claim 1, wherein all of the gas from the separator plate to the second rectifying plate are detachably formed on the wall surface of the vacuum container or on the fixing member on the vacuum container side. Coaxially and at least first
A ring-shaped base mount having a camera mount for accommodating all the members extending from the mixing spacer to the second rectifying plate in the axial direction, and a pressing plate formed as a ring-shaped body, A gas introduction apparatus for reduced pressure CVD, comprising a camera mount that fits into the mount, and a pressing ring that is attached to and detached from the base mount by rotation.